Mileage? Fuel pressure? Can you make a temporary blocking gasket for the egr valve? Make one from a soup can block off exhaust flow between the intake and exhaust ports underneath the egr valve, using it to hold in place. Drive. Another test is removing the front O2 sensor for an alternate exhaust hole before the catalytic converter. While loud, if engine power suddenly improves, the catcon is blocking exhaust flow. You might have to make a diverter to prevent hot exhaust gases from melting nearby plastic.

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Mileage? Fuel pressure? Can you make a temporary blocking gasket for the egr valve? Make one from a soup can block off exhaust flow between the intake and exhaust ports underneath the egr valve, using it to hold in place. Drive. Another test is removing the front O2 sensor for an alternate exhaust hole before the catalytic converter. While loud, if engine power suddenly improves, the catcon is blocking exhaust flow. You might have to make a diverter to prevent hot exhaust gases from melting nearby plastic.

Thank you for replying.

Mileage: 139, 000

I meant to put the o2 sensor is 40k miles in.

I dont have a fuel pressure tool.

EGR is brand new. I have 0 problems blocking the hole. I can test that later.

I feel like i may not have given enough information.

I was getting the p0300 code. I started by replacing the EGR. No fix.

I then replaced the coils, and wires three days ago.

I drove the car with zero issues for 200 miles.

I filled up gas this morning.

IMMEDIATELY afterwards, the car starting shaking, and the p0300 code came back.

I hope that makes sense.

Do i remove the o2 sensor, then start the car?

Thank you for your help.

My biggest question is: why did it drove fine but as soon as i put gas in... it goes bad?

Last edited by Seanmu; 07-12-2017 at 06:41 PM..
Reason: Put in more info

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Random problems sometimes have no rhyme or reason. To appreciate how complex EFI systems are, try reading how they work and throw in emissions monitoring while the engine is running. Whenever an error code appears (related to emissions - 'P' codes), emissions monitoring detected something amiss and triggers the error light while storing the error code for later retrieval. Gasoline is gasoline unless the station has a contaminated underground tank. If that occured, you're not alone as many other cars filling from the same pump will have contaminated fuel.

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so you replaced the egr...did you chip ut and clear the intake passage that is clogged up as well?...also you ecm is subtracting hella fuel from your long term trim.i suspect clogged exhaust..pull the manifold o2 sensor out and see how it does

...shure you can trust the government,just ask us indians all about it...

heavy line the final protective fire line of the dealership

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so you replaced the egr...did you chip ut and clear the intake passage that is clogged up as well?...also you ecm is subtracting hella fuel from your long term trim.i suspect clogged exhaust..pull the manifold o2 sensor out and see how it does

Did I chip UT and clear the intake passage? I sprayed the hell out of it with carb cleaner. My car smelled like carb cleaner for a week. Not sure if that did anything.

Should I leave the o2 sensor plugged in to the cable? Just remove the o2 from the mainfold?

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if the bolts arnt to rusty.drop the pipe to the manifold...if they are pull o2..then runn for a day if the misfire is gone plugged exhaust is issue..if it makes no difference clear the passages for both intake and exhaust..a carboned over port on the exhaust sidewill restrict flow as well as on intake side..it don't take much exhaust gass to lean out the mixture and cause a lean misfire...also plugged restricted injectors can cause same issue

...shure you can trust the government,just ask us indians all about it...

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102 kpa = 14.7 psi. If you are reading 102 kpa with ignition on, engine off, your map sensor is correctly outputting correct signals. Scientific measurements can be confusing and may be blamed on politics in collusion with American industry back when the metric system was suggested to replace the American SAE standard of measurement. As it is, the metric system is widely accepted everywhere in the world with America and Britain unable to completely accept it.

Its normal for different readers and scantools to display different measurements like inches of mercury (in hg), pounds per square inch (psi) or kilopascals (kpa). Add pressure measurements in absolute or gauge pressure and confusion scares away learning. The trick is to be aware of scientific measurements and whether absolute or gauge pressure is displayed. Knowing basic science helps too, like sea level atmospheric pressure is 14.7 psi/102 kpa. Conversion charts are available, online.

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Agreed. I assumed the OP could use the reader or whatever he used to get the Freeze Frame to read MAP with engine off, ignition on, but maybe not?

Quote:

Originally Posted by Seanmu

Is there a how-to to rigging a heat-shield to place in front of the O2 path? I figured just using a soda can. But where would I attach it to?

If you keep the engine run time really short, aluminum foil duct-taped on to the fan shroud or whatever is across the O2 should work. I often try and work duct-tape into things but that's just a personal thing

Or if you have AC, wrap the foil around the AC hoses there at the top with the foil length down long enough to block the exhaust gas. Starting off with a cold engine will help

As mentioned previously, knowing basic science helps. To understand and relate pressures or vacuum, some known facts are needed for perspective. Even I make mistakes. Ignore post #15 as its incorrect. I subtracted a psi value from in hg and arrived an an incorrect number. The corrected math is below.

Naturally aspirated engines are always sucking air into the intake manifold so a vacuum is always seen on vacuum/pressure gauges. Atmospheric pressure, when using sea level numbers, is always referenced as 14,7 psi. If you were to measure a vacuum, either a gauges can measure in negative pressure or pascals. Remember, a vacuum means suction so less than atmospheric pressure is expected when observing a vacuum gauge. No pressure is calibrated in negative pressures but they are calibrated either in kpa, bar or inches of mercury (in hg). 29.99 in hg is considered a near perfect vacuum. Using a vacuum/pressure gauge, zero+ = pressure, zero- = a vacuum. From zero in a vacuum/pressure gauge, engine off = zero gauge reading. Once running, the engine is always sucking in air so the intake manifold is in a vacuum and the vac/press gauge reads below 14.7. Since gauges aren't calibrated to read negative pressures, in hg is used. You may have seen various posts stating vacuum at idle between 15-21. That's 15in hg to 21 in hg, increasing numbers means increasing vacuum. Maximum vacuum is 29.99 in hg but cannot exist in real world intake manifolds but do exist when evacuating ac systems using a vacuum pump to remove air and create a near perfect void before installing refrigerant.

Confusion occurs because vacuum is never referenced as a negative pressure number because its incorrect terminology. Vacuum is always discussed in reference to inches of mercury or kilopascals with kpa being metric so terminology doesn't change like (positive) psi to (negative) in hg. Converting numbers can further confuse anyone without a perspective. The same vacuum value of 15-20 in hg can be converted to kpa but not into pressure as this isn't correct. The simplest references to use are known vacuum values with an idling engine (15-20in hg), 29.99 in hg as a perfect vacuum and sea level pressure at 14.7 psi. Working with measured numbers then requires converting to comfortable values easily understood compared to known values to arrive at either a correct value or error. An error would point to either incorrect conversion or sensor fault. The value of 14.7 psi converts to 102 kpa and is seen as (relative) sea level pressure for ignition on, engine off. The lower kpa of 51 fits with engine idling, a vacuum. Converting 51 kpa to 7.4 psi is correct but remember, this is a vacuum value and not positive pressure. Converting 51 kpa to in hg becomes 15 in hg, typical vacuum values with an idling engine.

Last edited by fdryer; 07-19-2017 at 02:11 PM..

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Ignore post #15 as its incorrect. I subtracted a psi value from in hg and arrived an an incorrect number. The corrected math is below.

Ah, thanks, I feel slightly less confused now

Quote:

The lower kpa of 51 fits with engine idling, a vacuum. Converting 51 kpa to 7.4 psi is correct but remember, this is a vacuum value and not positive pressure. Converting 51 kpa to in hg becomes 15 in hg, typical vacuum values with an idling engine.

That makes sense. I don't know how much vacuum an idling engine should pull at the intake - I asked for an engine off OBDII reading of the MAP because that's a number I can be relatively sure of